0« Muscular Motion and Animal Spirits 279 



aerial particles brought with the mass of the blood 

 should be transmitted into the brain and the nerves 

 arising in it. If the nitro-aerial particles are either 

 not carried in sufficient quantity to the brain, or are 

 unable to pass along the nerves on account of their 

 obstruction, the animal economy and the motive 

 function cannot but be disturbed. And from this 

 cause apoplexy, paralysis, and diseases of that kind 

 seem not rarely to originate, as has been stated 

 above. 



As the nitro-aerial particles have to be sent to the 

 brain, so on the other hand the saline-sulphureous 

 particles have to be altogether excluded from it ; 

 for if they, either on account of their extreme tenuity, 

 or because the passages of the brain are too open, 

 or on account of too intense fermentation of the 

 blood, make their way into the brain, they excite the 

 nitre-aerial particles, ?>., the animal spirits, to in- 

 ordinate motions. Hence the animal economy is 

 much perturbed, as probably happens in intoxica- 

 tion, epilepsy, and other diseases of the kind : for 

 liquors full of volatile sulphur, such as spirit of wine 

 and the chemical oils of vegetables, when taken too 

 quickly, not infrequently produce the diseases 

 mentioned. An observation which I have made 

 m(jre than once points in the same direction. For 

 I have known persons subject to paroxysms of a 

 maniacal sort and also convulsions, whose sputum, 

 while they were suffering from such paroxysms, 

 burst into flame like oil, or rather in the manner of 

 gunpowder, when it was put into the fire : it is indeed 

 probable that in this case the saline-sulphureous 

 particles of the blood had been carried so far that 

 they burst into the recesses of the brain and there 

 excited the animal spirits to inordinate motions. 



